The correct option is B Both
The word 'both' is used specifically to talk about two people / events / actions, which can definitely be discerned from the rest of the sentence. The word 'all', though is used to include every person / event / action, and unless the quantity of two is specified both will not be used. Thus, in the given sentence, Option B) - Both is the correct answer, as twins refers to two siblings. All the other options are inappropriate.